Contour pocket and hybrid susceptor for wafer uniformity

ABSTRACT

Susceptor assemblies comprising a susceptor base and a plurality of pie-shaped skins thereon are described. A pie anchor can be positioned in the center of the susceptor base to hold the pie-shaped skins in place during processing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. patent applicationSer. No. 15/616,364, Jun. 7, 2017, which claims priority to U.S.Provisional Application No. 62/347,062, filed Jun. 7, 2016, the entiredisclosure of which is hereby incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to pockets to support wafers ina susceptor. In particular, embodiments of the disclosure are directedto susceptor assemblies with wafer pockets for batch processingchambers.

BACKGROUND

In a batch processing chamber, film thickness, refractive index and wetetch rate uniformity are mostly dependent on pocket temperaturevariations in the radial and azimuthal directions. Some deposited films,like SiN, are very sensitive to thermal gradients and uniformity insidethe pocket in both directions. Thermal non-uniformity is morepredominant than RF non-uniformity on most films. Some current batchprocess chambers using carousel susceptors with one slit valve, fivezone heater coils are not enough to compensate for large thermalgradients (>10° C.) on the wafer even with zonal tuning and susceptorrotation. This may be due, in part, to cold spots near the slit valveand lift pins.

Current SiC coated graphite susceptors are large, monolithic andexpensive to clean. In order to get the susceptor cleaned, a sparesusceptor is kept to minimize chamber downtime. Whenever a new susceptoris installed, the flatness, runout and other measurements are documents.SiC coated materials are resistance to aqueous solutions of salts,organic reagents, some dilute acids (e.g., dilute HF, HCl, H₂SO₄, HNO₃)and hot inert gases. However, the SiC coating by itself is not inert anderodes faster under NF₃ plasma or fluorine, HF environments.

Therefore, there is a need in the art for apparatus and methods toincrease temperature uniformity across the wafer. There is also a needin the art for susceptors inert to the chamber environment.

SUMMARY

One or more embodiments of the disclosure are directed to susceptorassemblies comprising a susceptor base, a plurality of pie-shaped skinsand a pie anchor. The plurality of pie-shaped skins is on the susceptorbase. The pie anchor is in a center of the susceptor base and isconfigured to cooperatively interact with the pie-shaped skins to holdthe pie-shaped skins in place.

Additional embodiments of the disclosure are directed to susceptorassemblies comprising a susceptor base with a plurality of islandsextending above the susceptor base. The islands are sized to support asubstrate during processing. A plurality of skins are positioned tosurround the plurality of islands, each of the plurality of skins madefrom a ceramic material.

Further embodiments of the disclosure are directed to susceptorassemblies comprising a susceptor base with a plurality of recesses withpocket covers within the recesses. The pocket covers have a thicknesssubstantially the same as the depth of the recesses. A plurality ofpie-shaped skins is on the susceptor base. Each of the pie-shaped skinshas at least one recess or protrusion adjacent an inner peripheral edgeof the pie-shaped skin. A pie anchor is in a center of the susceptorbase. The pie anchor is configured to cooperatively interact with thepie-shaped skins to hold the pie-shaped skins in place. The pie anchorcomprises at least one protrusion sized to cooperatively interact withthe at least one recess or at least one recess sized to cooperativelyinteract with the at least one protrusion on the pie-shaped skins. Aclamp plate is positioned over the anchor and inner peripheral edge ofthe skins.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 shows a cross-sectional view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 2 shows a partial perspective view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 3 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 4 shows a schematic view of a portion of a wedge shaped gasdistribution assembly for use in a batch processing chamber inaccordance with one or more embodiment of the disclosure;

FIG. 5 shows a schematic view of a batch processing chamber inaccordance with one or more embodiment of the disclosure; and

FIG. 6 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIG. 7 shows an anchor in a susceptor assembly in accordance with one ormore embodiment of the disclosure;

FIG. 8 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIG. 9 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIG. 10 shows a pocket cover for a susceptor assembly in accordance withone or more embodiment of the disclosure;

FIG. 11 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIG. 12 shows a lift pin for use with a susceptor assembly in accordancewith one or more embodiment of the disclosure;

FIG. 13 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIG. 14 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIG. 15 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIG. 16 shows a skin for use with the embodiment of FIG. 15 ;

FIG. 17 shows a susceptor assembly in accordance with one or moreembodiment of the disclosure;

FIGS. 18A and 18B show pocket designs in accordance with one or moreembodiment of the disclosure;

FIGS. 19A and 19B show pocket designs in accordance with one or moreembodiments of the disclosure;

FIG. 20 shows a pocket design in accordance with one or more embodimentof the disclosure;

FIG. 21 shows a pocket design in accordance with one or more embodimentof the disclosure;

FIG. 22 shows a pocket design in accordance with one or more embodimentof the disclosure; and

FIGS. 23A and 23B show pocket designs in accordance with one or moreembodiment of the disclosure.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

A “substrate” as used herein, refers to any substrate or materialsurface formed on a substrate upon which film processing is performedduring a fabrication process. For example, a substrate surface on whichprocessing can be performed include materials such as silicon, siliconoxide, strained silicon, silicon on insulator (SOI), carbon dopedsilicon oxides, amorphous silicon, doped silicon, germanium, galliumarsenide, glass, sapphire, and any other materials such as metals, metalnitrides, metal alloys, and other conductive materials, depending on theapplication. Substrates include, without limitation, semiconductorwafers. Substrates may be exposed to a pretreatment process to polish,etch, reduce, oxidize, hydroxylate, anneal and/or bake the substratesurface. In addition to film processing directly on the surface of thesubstrate itself, in the present disclosure, any of the film processingsteps disclosed may also be performed on an under-layer formed on thesubstrate as disclosed in more detail below, and the term “substratesurface” is intended to include such under-layer as the contextindicates. Thus for example, where a film/layer or partial film/layerhas been deposited onto a substrate surface, the exposed surface of thenewly deposited film/layer becomes the substrate surface.

As used in this specification and the appended claims, the terms“precursor”, “reactant”, “reactive gas” and the like are usedinterchangeably to refer to any gaseous species that can react with thesubstrate surface.

FIG. 1 shows a cross-section of a processing chamber 100 including a gasdistribution assembly 120, also referred to as injectors or an injectorassembly, and a susceptor assembly 140. The gas distribution assembly120 is any type of gas delivery device used in a processing chamber. Thegas distribution assembly 120 includes a front surface 121 which facesthe susceptor assembly 140. The front surface 121 can have any number orvariety of openings to deliver a flow of gases toward the susceptorassembly 140. The gas distribution assembly 120 also includes an outerperipheral edge 124 which in the embodiments shown, is substantiallyround.

The specific type of gas distribution assembly 120 used can varydepending on the particular process being used. Embodiments of thedisclosure can be used with any type of processing system where the gapbetween the susceptor and the gas distribution assembly is controlled.While various types of gas distribution assemblies can be employed(e.g., showerheads), embodiments of the disclosure may be particularlyuseful with spatial gas distribution assemblies which have a pluralityof substantially parallel gas channels. As used in this specificationand the appended claims, the term “substantially parallel” means thatthe elongate axis of the gas channels extend in the same generaldirection. There can be slight imperfections in the parallelism of thegas channels. In a binary reaction, the plurality of substantiallyparallel gas channels can include at least one first reactive gas Achannel, at least one second reactive gas B channel, at least one purgegas P channel and/or at least one vacuum V channel. The gases flowingfrom the first reactive gas A channel(s), the second reactive gas Bchannel(s) and the purge gas P channel(s) are directed toward the topsurface of the wafer. Some of the gas flow moves horizontally across thesurface of the wafer and out of the process region through the purge gasP channel(s). A substrate moving from one end of the gas distributionassembly to the other end will be exposed to each of the process gasesin turn, forming a layer on the substrate surface.

In some embodiments, the gas distribution assembly 120 is a rigidstationary body made of a single injector unit. In one or moreembodiments, the gas distribution assembly 120 is made up of a pluralityof individual sectors (e.g., injector units 122), as shown in FIG. 2 .Either a single piece body or a multi-sector body can be used with thevarious embodiments of the disclosure described.

A susceptor assembly 140 is positioned beneath the gas distributionassembly 120. The susceptor assembly 140 includes a top surface 141 andat least one recess 142 in the top surface 141. The susceptor assembly140 also has a bottom surface 143 and an edge 144. The recess 142 can beany suitable shape and size depending on the shape and size of thesubstrates 60 being processed. In the embodiment shown in FIG. 1 , theat least one recess 142 has a flat bottom to support the bottom of thewafer; however, the bottom of the recess can vary. In some embodiments,the recess has step regions around the outer peripheral edge of therecess which are sized to support the outer peripheral edge of thewafer. The amount of the outer peripheral edge of the wafer that issupported by the steps can vary depending on, for example, the thicknessof the wafer and the presence of features already present on the backside of the wafer.

In some embodiments, as shown in FIG. 1 , the recess 142 in the topsurface 141 of the susceptor assembly 140 is sized so that a substrate60 supported in the recess 142 has a top surface 61 substantiallycoplanar with the top surface 141 of the susceptor 140. As used in thisspecification and the appended claims, the term “substantially coplanar”means that the top surface of the wafer and the top surface of thesusceptor assembly are coplanar within ±0.2 mm. In some embodiments, thetop surfaces are coplanar within 0.5 mm, ±0.4 mm, ±0.35 mm, ±0.30 mm,±0.25 mm, ±0.20 mm, ±0.15 mm, ±0.10 mm or ±0.05 mm.

The susceptor assembly 140 of FIG. 1 includes a support post 160 whichis capable of lifting, lowering and rotating the susceptor assembly 140.The susceptor assembly may include a heater, or gas lines, or electricalcomponents within the center of the support post 160. The support post160 may be the primary means of increasing or decreasing the gap betweenthe susceptor assembly 140 and the gas distribution assembly 120, movingthe susceptor assembly 140 into proper position. The susceptor assembly140 may also include fine tuning actuators 162 which can makemicro-adjustments to susceptor assembly 140 to create a predeterminedgap 170 between the susceptor assembly 140 and the gas distributionassembly 120.

In some embodiments, the gap 170 distance is in the range of about 0.1mm to about 5.0 mm, or in the range of about 0.1 mm to about 3.0 mm, orin the range of about 0.1 mm to about 2.0 mm, or in the range of about0.2 mm to about 1.8 mm, or in the range of about 0.3 mm to about 1.7 mm,or in the range of about 0.4 mm to about 1.6 mm, or in the range ofabout 0.5 mm to about 1.5 mm, or in the range of about 0.6 mm to about1.4 mm, or in the range of about 0.7 mm to about 1.3 mm, or in the rangeof about 0.8 mm to about 1.2 mm, or in the range of about 0.9 mm toabout 1.1 mm, or about 1 mm.

The processing chamber 100 shown in the Figures is a carousel-typechamber in which the susceptor assembly 140 can hold a plurality ofsubstrates 60. As shown in FIG. 2 , the gas distribution assembly 120may include a plurality of separate injector units 122, each injectorunit 122 being capable of depositing a film on the wafer, as the waferis moved beneath the injector unit. Two pie-shaped injector units 122are shown positioned on approximately opposite sides of and above thesusceptor assembly 140. This number of injector units 122 is shown forillustrative purposes only. It will be understood that more or lessinjector units 122 can be included. In some embodiments, there are asufficient number of pie-shaped injector units 122 to form a shapeconforming to the shape of the susceptor assembly 140. In someembodiments, each of the individual pie-shaped injector units 122 may beindependently moved, removed and/or replaced without affecting any ofthe other injector units 122. For example, one segment may be raised topermit a robot to access the region between the susceptor assembly 140and gas distribution assembly 120 to load/unload substrates 60.

Processing chambers having multiple gas injectors can be used to processmultiple wafers simultaneously so that the wafers experience the sameprocess flow. For example, as shown in FIG. 3 , the processing chamber100 has four gas injector assemblies and four substrates 60. At theoutset of processing, the substrates 60 can be positioned between thegas distribution assemblies 120. Rotating 17 the susceptor assembly 140by 45° will result in each substrate 60 which is between gasdistribution assemblies 120 to be moved to an gas distribution assembly120 for film deposition, as illustrated by the dotted circle under thegas distribution assemblies 120. An additional 45° rotation would movethe substrates 60 away from the gas distribution assemblies 120. Thenumber of substrates 60 and gas distribution assemblies 120 can be thesame or different. In some embodiments, there are the same numbers ofwafers being processed as there are gas distribution assemblies. In oneor more embodiments, the number of wafers being processed are fractionof or an integer multiple of the number of gas distribution assemblies.For example, if there are four gas distribution assemblies, there are 4xwafers being processed, where x is an integer value greater than orequal to one. In an exemplary embodiment, the gas distribution assembly120 includes eight process regions separated by gas curtains and thesusceptor assembly 140 can hold six wafers.

The processing chamber 100 shown in FIG. 3 is merely representative ofone possible configuration and should not be taken as limiting the scopeof the disclosure. Here, the processing chamber 100 includes a pluralityof gas distribution assemblies 120. In the embodiment shown, there arefour gas distribution assemblies (also called gas distributionassemblies 120) evenly spaced about the processing chamber 100. Theprocessing chamber 100 shown is octagonal; however, those skilled in theart will understand that this is one possible shape and should not betaken as limiting the scope of the disclosure. The gas distributionassemblies 120 shown are trapezoidal, but can be a single circularcomponent or made up of a plurality of pie-shaped segments, like thatshown in FIG. 2 .

The embodiment shown in FIG. 3 includes a load lock chamber 180, or anauxiliary chamber like a buffer station. This chamber 180 is connectedto a side of the processing chamber 100 to allow, for example thesubstrates (also referred to as substrates 60) to be loaded/unloadedfrom the processing chamber 100. A wafer robot may be positioned in thechamber 180 to move the substrate onto the susceptor.

Rotation of the carousel (e.g., the susceptor assembly 140) can becontinuous or intermittent (discontinuous). In continuous processing,the wafers are constantly rotating so that they are exposed to each ofthe injectors in turn. In discontinuous processing, the wafers can bemoved to the injector region and stopped, and then to the region 84between the injectors and stopped. For example, the carousel can rotateso that the wafers move from an inter-injector region across theinjector (or stop adjacent the injector) and on to the nextinter-injector region where the carousel can pause again. Pausingbetween the injectors may provide time for additional processing stepsbetween each layer deposition (e.g., exposure to plasma).

FIG. 4 shows a sector or portion of a gas distribution assembly 120,which may be referred to as an injector unit 122. The injector units 122can be used individually or in combination with other injector units.For example, as shown in FIG. 5 , four of the injector units 122 of FIG.4 are combined to form a single gas distribution assembly 120. (Thelines separating the four injector units are not shown for clarity.)While the injector unit 122 of FIG. 4 has both a first reactive gas port125 and a second gas port 135 in addition to purge gas ports 155 andvacuum ports 145, an injector unit 122 does not need all of thesecomponents.

Referring to both FIGS. 4 and 5 , a gas distribution assembly 120 inaccordance with one or more embodiment may comprise a plurality ofsectors (or injector units 122) with each sector being identical ordifferent. The gas distribution assembly 120 is positioned within theprocessing chamber and comprises a plurality of elongate gas ports 125,135, 155 and vacuum ports 145 in a front surface 121 of the gasdistribution assembly 120. The plurality of elongate gas ports 125, 135,155 and vacuum ports 145 extend from an area adjacent the innerperipheral edge 123 toward an area adjacent the outer peripheral edge124 of the gas distribution assembly 120. The plurality of gas portsshown include a first reactive gas port 125, a second gas port 135, avacuum port 145 which surrounds each of the first reactive gas ports andthe second reactive gas ports and a purge gas port 155.

With reference to the embodiments shown in FIG. 4 or 5 , when statingthat the ports extend from at least about an inner peripheral region toat least about an outer peripheral region, however, the ports can extendmore than just radially from inner to outer regions. The ports canextend tangentially as vacuum port 145 surrounds reactive gas port 125and reactive gas port 135. In the embodiment shown in FIGS. 4 and 5 ,the wedge shaped reactive gas ports 125, 135 are surrounded on alledges, including adjacent the inner peripheral region and outerperipheral region, by a vacuum port 145.

Referring to FIG. 4 , as a substrate moves along path 127, each portionof the substrate surface is exposed to the various reactive gases. Tofollow the path 127, the substrate will be exposed to, or “see”, a purgegas port 155, a vacuum port 145, a first reactive gas port 125, a vacuumport 145, a purge gas port 155, a vacuum port 145, a second gas port 135and a vacuum port 145. Thus, at the end of the path 127 shown in FIG. 4, the substrate has been exposed to the first reactive gas from a firstreactive gas port 125 and the second reactive gas from the secondreactive gas port 135 to form a layer. The injector unit 122 shown makesa quarter circle but could be larger or smaller. The gas distributionassembly 120 shown in FIG. 5 can be considered a combination of four ofthe injector units 122 of FIG. 4 connected in series.

The injector unit 122 of FIG. 4 shows a gas curtain 150 that separatesthe reactive gases. The term “gas curtain” is used to describe anycombination of gas flows or vacuum that separate reactive gases frommixing. The gas curtain 150 shown in FIG. 4 comprises the portion of thevacuum port 145 next to the first reactive gas port 125, the purge gasport 155 in the middle and a portion of the vacuum port 145 next to thesecond gas port 135. This combination of gas flow and vacuum can be usedto prevent or minimize gas phase reactions of the first reactive gas andthe second reactive gas.

Referring to FIG. 5 , the combination of gas flows and vacuum from thegas distribution assembly 120 form a separation into a plurality ofprocess regions 250. The process regions are roughly defined around theindividual gas ports 125, 135 with the gas curtain 150 between 250. Theembodiment shown in FIG. 5 makes up eight separate process regions 250with eight separate gas curtains 150 between. A processing chamber canhave at least two process region. In some embodiments, there are atleast three, four, five, six, seven, eight, nine, 10, 11 or 12 processregions.

During processing a substrate may be exposed to more than one processregion 250 at any given time. However, the portions that are exposed tothe different process regions will have a gas curtain separating thetwo. For example, if the leading edge of a substrate enters a processregion including the second gas port 135, a middle portion of thesubstrate will be under a gas curtain 150 and the trailing edge of thesubstrate will be in a process region including the first reactive gasport 125.

A factory interface 280, which can be, for example, a load lock chamber,is shown connected to the processing chamber 100. A substrate 60 isshown superimposed over the gas distribution assembly 120 to provide aframe of reference. The substrate 60 may often sit on a susceptorassembly to be held near the front surface 121 of the gas distributionplate 120. The substrate 60 is loaded via the factory interface 280 intothe processing chamber 100 onto a substrate support or susceptorassembly (see FIG. 3 ). The substrate 60 can be shown positioned withina process region because the substrate is located adjacent the firstreactive gas port 125 and between two gas curtains 150. Rotating thesubstrate 60 along path 127 will move the substrate counter-clockwisearound the processing chamber 100. Thus, the substrate 60 will beexposed to the first process region 250 a through the eighth processregion 250 h, including all process regions between.

Embodiments of the disclosure are directed to processing methodscomprising a processing chamber 100 with a plurality of process regions250 a-250 h with each process region separated from an adjacent regionby a gas curtain 150. For example, the processing chamber shown in FIG.5 . The number of gas curtains and process regions within the processingchamber can be any suitable number depending on the arrangement of gasflows. The embodiment shown in FIG. 5 has eight gas curtains 150 andeight process regions 250 a-250 h.

A plurality of substrates 60 are positioned on a substrate support, forexample, the susceptor assembly 140 shown FIGS. 1 and 2 . The pluralityof substrates 60 are rotated around the process regions for processing.Generally, the gas curtains 150 are engaged (gas flowing and vacuum on)throughout processing including periods when no reactive gas is flowinginto the chamber.

Wafer temperature mapping can be deduced based on growth per cycle.Current batch processing chamber pockets have thinner SiN/SAC films atthe center 3″ diameter because of a deeper valley in the center. Thefull wafer contact at 12 mm wide outer diameter seal band shows athicker film at the wafer outer diameter. This translates into colderwafer centers and thick wafer edges. Similar phenomena have beenobserved at the lift pin seal bands positioned at varying degrees.Thermal modeling has shown similar trends from thermal conductivityvariations. The valley depth and full contact areas of the wafer can beused as knobs to mitigate or enhance temperature profiles for differentapplications, like dielectric, metal or structure wafers. On structurewafers, thicker films occur near the loading areas. Some embodiments ofthe disclosure advantageously mitigate temperature non-uniformity byusing lower thermal conductive materials like alumina or quartz atstrategic places where hot spots are observed.

Some embodiments advantageously provide reduced thickness variation byproviding a contoured pocket design which has an inner diameter andouter diameter full contact. In some embodiments, the pocket design isadvantageously deep trenches on the outer diameters of the pocket. Oneor more embodiments advantageously provide alumina rings to drop waferedge temperatures.

One or more embodiments advantageously provide thin pie-shaped skins ontop of SiC-graphite substrate to keep the flat and parallel forperformance and longevity. In some embodiments, the hybrid susceptorprovides easily replaceable 60° pies for fast and inexpensive recycling.In some embodiments, pies are made from materials including aluminum,AlN, SiC, and materials that can be used for inertness to NF₃, chlorineand O₂/O₃ attacks from in-situ plasma. Some embodiments providesecondary coatings (HPM®, Durablock®, Duracoat®, yttria, AsMy, etc.)that can be used on the pie for increased resistance to erosivechemicals. In one or more embodiments, multiple base materials (e.g.,pure graphite, SiC coated graphite, stainless steel, aluminum) areemployed. In some embodiments, the base can be made of stainlesssteel/aluminum/graphite bolted/welded frames. In some embodiments, thepie shaped skins are made out of flat SiC-graphite for faster cleaningcycles. In some embodiments, the pie shaped skins can deliver vacuum orother inert gases to the wafer pockets with chucking and purgecapabilities. In one or more embodiments, the wafer thermal and filmthickness uniformity is increased with pie shaped quartz skins that canbe placed on areas between the pockets. In some embodiments, alumina orquartz rings can be placed inside the pockets for thermal andfilm-thickness uniformity improvement.

FIG. 6 shows an embodiment of a susceptor assembly 140 in accordancewith one or more embodiment of the disclosure. The susceptor assembly140 shown is configured to carry six wafers during processing. Thesusceptor assembly 140 can incorporate wafer chucking capabilitiesand/or grounding capabilities for plasma processes.

Monolithic aluminum susceptors have been observed to droop at 400° C.,which is the annealing temperature of the material base. The aluminumsusceptor base may be supported at the center with no support at theouter diameter. Stresses built from thermal non-uniformity, the weightof the susceptor itself and/or rotation can cause the drooping to occurover time. Therefore, some embodiments incorporate a graphite base tominimize or eliminate drooping and minimize stress on the susceptorbase.

The susceptor assembly 140 embodiment shown in FIG. 6 includes asusceptor base 310, an optional pocket cover 330, a pie skin 350 and apie anchor 370. The susceptor base 310 can be made from any suitablematerial including, but not limited to, graphite. The thickness of thesusceptor base 310 can be in the range of about 10 mm to about 50 mm, orin the range of about 20 mm to about 40 mm. In some embodiments, thesusceptor base 310 is about 30 mm thick. The thickness of the susceptorbase 310 is measured as the distance between the bottom surface 313 andthe top surface 314.

The pie skin 350 can cover a portion of the susceptor base 310 so that aplurality of pie skins 350 can be arranged to cover the susceptor base310. In the embodiment shown there are six pie skins 350 arranged toform a circular component covering the susceptor base 310. The angle ofthe pie skins 350 can vary depending on, for example, the number ofskins used to cover the base. For example, each of the pie skins 350 inFIG. 6 has an angle of about 60°. In some embodiments, there are in therange of about 2 to about 24 pie skins 350, or in the range of about 3to about 12 pie skins, or in the range of about 4 to about 8 pie skins.In some embodiments, there are 3, 4 or 6 pie skins 350.

The pie skins can be made from any suitable material. Suitable materialsmay be corrosion resistance including, but not limited to, aluminum,aluminum nitride, aluminum oxide, nitride or oxide coated materials.

The thickness of the skin 350, measured from the bottom surface 352 tothe top surface 354 is generally small relative to the thickness of thebase 310. In some embodiments, the pie skin 350 is in the range of about2 mm to about 12 mm thick, or in the range of about 3 mm to about 10 mmthick. In some embodiments, the pie skin 350 is about 6 mm thick. In oneor more embodiments, the pie skin 350 has a thickness greater than about3 mm, 4 mm, 5 mm, 6 mm, 7 mm or 8 mm. The thickness of the susceptorassembly 140 can be measured as the combined thickness of the susceptorbase 310 and the pie skin 350. The thickness of the susceptor assemblyof some embodiments is in the range of about 20 mm to about 60 mm, or inthe range of about 25 mm to about 50 mm, or in the range of about 30 mmto about 40 mm, or about 33 mm to about 37 mm.

The pie skin 350 can include a pocket 360 sized to support a waferduring processing. The pocket 360 of some embodiments has a depth in therange of about 2 mm to about 12 mm, or in the range of about 3 mm toabout 11 mm, or in the 4 mm to about 10 mm, or in the range of about 6mm to about 8 mm. In some embodiments, the pocket 360 is about 8 mmdeep.

The pie skin 350 can be held in place by friction or some suitablemechanical connection. In some embodiments, as shown in FIGS. 6 and 7 ,the pie skin 350 is held in place using a pie anchor 370 with a pieanchor pin 372. The anchor pin 372 can be a protrusion in the pie anchor370 that cooperatively interacts with a pie recess 356 in the skin 350.The pie anchor 370 shown in FIG. 7 has six anchor pins 372 to hold sixskins 350 at the same time. While the embodiments shown have aprotrusion on the anchor and a recess in the skin, those skilled in theart will understand that these are merely exemplary and should not betaken as limiting the scope of the disclosure. In some embodiments, thepie anchor 372 has a recess 371 that cooperatively interacts with aprotrusion 357 on the skin 350 (e.g., on the bottom of the skin 350).The number of protrusions 357 for each pie skin 350 can vary.

In the embodiment shown in FIG. 6 , there is only one protrusionextending from the pie anchor 370. In some embodiments, there is morethan one protrusion extending from the pie anchor 370. In one or moreembodiments, there is at least one protrusion extending from the pieanchor and at least one protrusion extending from the base 310 near anouter peripheral edge of the base 310 so that each pie skin 350 is heldin place by at least one protrusion near the inner peripheral edge andat least one protrusion near the outer peripheral edge. FIG. 9 shows analignment pin (protrusion 317) near the outer peripheral edge 315 of thebase 310.

The shape of the pie anchor 370 can vary. In the embodiment shown inFIGS. 6 and 7 , the pie anchor 370 is round and has a shape thatcooperatively interacts with, or matches, the shape of the innerperipheral edge 351 of the skin 350. The embodiment shown in FIG. 9 hasa hexagonal pie anchor 370 and the skins 350 have a flat innerperipheral edge 351.

FIG. 8 shows an embodiment of a susceptor assembly 140 with a pluralityof pie skins 350 having a radiused inner peripheral edge 351 with aledge 353. A clamp plate 378 can be connected to the susceptor base 310to clamp the pie skins 350 in place by pressing on the ledges 353 of theskins 350. The clamp plate 378 can be bolted to a pin (e.g., a stainlesssteel pin or sleeve) that extends into the susceptor base 310.

In use, the temperature in the processing chamber will cause expansionof the skin 350 and the pocket cover 330. FIG. 10 shows a partial viewof a susceptor base 310 with a pocket cover 330 in the recess of thesusceptor base 310. The pocket cover 330 has three slots 332 positionedadjacent the lift pins 312 to allow the lift pins 312 to pass throughthe slots 332. The slots are elongated in the direction of expansion sothat upon heating and expansion of the pocket cover 330, the slots 332do not interfere with movement of the lift pins 312.

The pocket cover 330 may be used to fill the pocket in the base 310, ifthere is one present. For example, an existing susceptor assembly mayhave a plurality of pockets formed in the base and the pocket covers 330may provide a flat surface to support the pie skins 350.

In some embodiments, as shown in FIG. 11 , the susceptor assembly 140includes three pie skins 350. Each of the pie skins 350 has an angle ofabout 120°. The smaller number of pie skins in FIG. 11 may be useful tominimize the penetration of gas to the base 310 through a smaller numberof seams than that of FIG. 9 . Each pie skin 350 can interact with atleast two alignment pins 317 near the outer peripheral edge or the innerperipheral edge of the pie skin 350.

FIG. 12 shows lift pins 312 incorporated into a ceramic sleeve 391positioned within a radial slot 392 in the base 310. The sleeve 391shown has a t-shaped body with arms 393 that can be sandwiched betweenthe base 310 and the pie skin 350.

In some embodiments, as shown in FIG. 13 , the susceptor assembly 140has no pockets in the stop surface. FIG. 13 shows a single component topto the susceptor assembly; however, those skilled in the art willunderstand that the top can be made up of a plurality of skins 350 asdescribed herein. The single component susceptor is shown for ease ofillustration and description only and should not be taken as limitingthe scope of the disclosure.

Each of the pockets shown in FIG. 13 can have different characteristics.For example, pockets P1, P2 and P3 have a 5.5 mm outer diameter ledge396, a flat interior 397 with a center chuck 398. Pockets P4 and P5 havea 12.5 mm outer diameter ledge 396, a flat interior 397 with a 10 mmoffset chuck 398. Pocket P6 has a 12.5 mm outer diameter ledge 396, aflat interior 397 and a 25 mm offset chuck 398. The chuck 398 forms afluid connection to a vacuum source and optionally a purge gas source.The vacuum source can be used to chuck the wafer so that there is littleor no movement during processing. The optional purge gas source can beused for a back side purge or to release a chucked wafer by applyingbackside pressure.

FIG. 14 shows a susceptor recess with a ledge 396 with a ring 399. Thering 399 can be made from any suitable material including, but notlimited to, alumina, quarts, graphite, silicon carbide and SiC-graphite.The use of an edge ring 399 may allow for tuning of the thickness and/orproperties of the edge ring by using different materials, thicknesses,contact area, roughness, etc. The edge ring 399 may provide an easilyreplaceable or serviceable component.

FIG. 15 shows another embodiment in which a susceptor base 310 has aplurality of islands 410 which will serve to support a wafer duringprocessing. The islands can have any suitable height. In someembodiments, the islands 410 have a height in the range of about 2 mm toabout 5 mm, or about 3 mm.

A plurality of skins 420 are positioned between and surrounding theislands 410. The skins 420 have an inner peripheral edge 422 and anouter peripheral edge 424 and a thickness. At least one cutout 425 inthe skin 420 is sized to surround the island 410. Each skin has athickness in the range of about 2 mm to about 10 mm. In someembodiments, the thickness of the skin 420 is about 3 mm. In one or moreembodiments, the skin 420 has a thickness that is substantially the sameas the height of the islands 410. In some embodiments, the thickness ofthe skin 420 is greater than the height of the island 410 so that arecess is formed when the skin 420 is positioned to surround the islands410. In some embodiments, the thickness of the skin 420 is greater thanthe height of the island 410 by an amount substantially the same as thethickness of the wafer being processed.

FIG. 17 shows another embodiment of a susceptor assembly 140 combiningthe islands 410 with skin 420 and the ring 399. In some embodiments, thesusceptor base 310 is graphite, the ring 399 is quartz or alumina andthe skin 420 is quartz.

The inventors have found that studying the thermal or film thickness mapof a wafer on a carousel susceptor can give clear thermal signatures(hot or cold) areas that can be compensated for thermal or filmthickness uniformity. Current pocket 500 designs (POR), as shown inFIGS. 18A and 18B, have an outer peripheral edge 510 with three zones520, 530, 540. FIG. 18B shows a partial cross-section of the recess withthree valley heights of 2 mil-3 mil-4 mil (center)-3 mil-2 mil valleyswhich is populated with hundreds of small 2.5 mm diameter mesas 550.Large thermal ripples (between the concentric circles of mesas which are15 mm apart) of greater than 1° C. are seen along with a wafer edgetemperature rise of >1° C. Radially, there is a total drop of about15.5° C. going from outer diameter of pocket to center of pocket. Thisthermal drop gives several multiples of film thickness drops.

An embodiment of a pocket 500 shown in FIG. 19A has inverse valleys toimprove uniformity and conformality of films. Current pocket has 2 mil-3mil-4 mil (center)-3 mil-2 mil across a diameter, with top of mesa onsame plane as the outer diameter seal ledge. An inverse valley has 4mil-3 mil-2 mil (center)-3 mil-4 mil or 3 mil-3 mil-2 mil (center)-3mil-3 mil. Every 1 mil increase in valley depth increases temperature byabout 1° C. on wafer. FIG. 19B shows a graph of the film thickness as afunction of wafer location in the pocket with zero at the center of thepocket. It can be seen that the film thickness for the inverse valleysis more uniform than the POR pocket.

In another embodiment, a thin (2-3 mm thick) ceramic (Alumina, Quartz)L-shaped (in cross-section) ring insert sits in a tightly machinedcircular channel in the pocket around the outer diameter of the pocket.Because of lower thermal conductivity of Alumina or Quartz, the waferthermal uniformity is brought down from 15.5° C. to 9.1° C. with Aluminaand to 4.4° C. with Quartz rings. Some embodiments do not include aceramic insert but have an inert gas flowing through the circularchannel. Because nitrogen gas has low thermal conductivity, theuniformity is increased. However, the gas flow might be managed toprevent trapping of process gases and parasitic CVD reactions.

The embodiment shown in FIG. 20 includes a contoured pocket 500 designwhere the hot spots/arcs (typically at 4'O clock & 8'O clock positions)on wafer edge are mitigated by digging a 6 mil deep trench 560 wide andlong enough to equalize temperature on wafer. Because of the trench 560there is no direct contact of thermally conductive silicon carbide withthe wafer and hence the temperature drops. The embodiment shown has aflat segment 562 bisecting the two trench 560 regions.

Another embodiment, as shown in FIG. 21 , has a flat pocket 500 design.A thermal study indicated that higher contact area with the wafer givesa faster equilibration time to steady state and better through-puttimes. The flat pocket design, which provides full contact, does nothave any mesas. The pocket 500 includes a few cross-grooves 570 of 1 mmwide×6 mil deep, just enough for vacuum chucking the wafer down. In someembodiments, the cross-grooves have a width in the range of about 0.5 mmto about 2 mm and a depth in the range of about 2 mil to about 10 mil.It was observed that there were no thermal ripples observed.

Another embodiment, as shown in FIG. 22 , has slightly wider pocketdiameters to mitigate wafer edge chipping 67 issues and reduce waferedge temperature around the perimeter of wafer. In the embodiment shown,the top of the pocket has a diameter about 1 mm greater than the bottomof the pocket resulting in an angle θ of about 15°. In some embodiments,the angle formed by the difference in diameter of the top of the pocketand the bottom of the pocket is in the range of about 5° to about 30°,or in the range of about 10° to about 20°.

FIGS. 23A and 23B show another embodiment of a pocket 500 with improvedchucking force at higher speeds of susceptor rotation. More vacuumgrooves can be created with a honeycomb pocket design with denselypopulated large mesas of about 10 mm. The mesas can have diameters inthe range of about 5 mm to about 15 mm. According to a thermal study, itwas found that higher contact area with wafer gives faster time tosteady state for better through-put times. The valley depths betweenmesas can be kept to about 1 mil, 2 mil, 3 mil or 4 mil. Without beingbound by any theory of operation, it is believed that the honeycombdesign has densely populated mesas in x-y direction merging withcircular pocket ledge, there may be some partial mesas, the minimum sizeof which are kept at >2 mm (>1.5 mm, >2.5 mm or >3 mm), because ofmachinability issue. Also a 2 mm (1 mm to 3 mm) wide spacing is keptbetween the inner ledge of pocket to the nearest mesa. This designcreates a very low thermal ripple of <0.2° C. and an edge temperaturerise of 0.4° C. FIG. 23B shows a graph of the temperature as a functionof position from the center of the pocket.

According to one or more embodiments, the substrate is subjected toprocessing prior to and/or after forming the layer. This processing canbe performed in the same chamber or in one or more separate processingchambers. In some embodiments, the substrate is moved from the firstchamber to a separate, second chamber for further processing. Thesubstrate can be moved directly from the first chamber to the separateprocessing chamber, or it can be moved from the first chamber to one ormore transfer chambers, and then moved to the separate processingchamber. Accordingly, the processing apparatus may comprise multiplechambers in communication with a transfer station. An apparatus of thissort may be referred to as a “cluster tool” or “clustered system,” andthe like.

Generally, a cluster tool is a modular system comprising multiplechambers which perform various functions including substratecenter-finding and orientation, annealing, annealing, deposition and/oretching. According to one or more embodiments, a cluster tool includesat least a first chamber and a central transfer chamber. The centraltransfer chamber may house a robot that can shuttle substrates betweenand among processing chambers and load lock chambers. The transferchamber is typically maintained at a vacuum condition and provides anintermediate stage for shuttling substrates from one chamber to anotherand/or to a load lock chamber positioned at a front end of the clustertool. Two well-known cluster tools which may be adapted for the presentdisclosure are the Centura® and the Endura®, both available from AppliedMaterials, Inc., of Santa Clara, Calif. However, the exact arrangementand combination of chambers may be altered for purposes of performingspecific steps of a process as described herein. Other processingchambers which may be used include, but are not limited to, cyclicallayer deposition (CLD), atomic layer deposition (ALD), chemical vapordeposition (CVD), physical vapor deposition (PVD), etch, pre-clean,chemical clean, thermal treatment such as RTP, plasma nitridation,anneal, orientation, hydroxylation and other substrate processes. Bycarrying out processes in a chamber on a cluster tool, surfacecontamination of the substrate with atmospheric impurities can beavoided without oxidation prior to depositing a subsequent film.

According to one or more embodiments, the substrate is continuouslyunder vacuum or “load lock” conditions, and is not exposed to ambientair when being moved from one chamber to the next. The transfer chambersare thus under vacuum and are “pumped down” under vacuum pressure. Inertgases may be present in the processing chambers or the transferchambers. In some embodiments, an inert gas is used as a purge gas toremove some or all of the reactants. According to one or moreembodiments, a purge gas is injected at the exit of the depositionchamber to prevent reactants from moving from the deposition chamber tothe transfer chamber and/or additional processing chamber. Thus, theflow of inert gas forms a curtain at the exit of the chamber.

The substrate can be processed in single substrate deposition chambers,where a single substrate is loaded, processed and unloaded beforeanother substrate is processed. The substrate can also be processed in acontinuous manner, similar to a conveyer system, in which multiplesubstrate are individually loaded into a first part of the chamber, movethrough the chamber and are unloaded from a second part of the chamber.The shape of the chamber and associated conveyer system can form astraight path or curved path. Additionally, the processing chamber maybe a carousel in which multiple substrates are moved about a centralaxis and are exposed to deposition, etch, annealing, cleaning, etc.processes throughout the carousel path.

During processing, the substrate can be heated or cooled. Such heatingor cooling can be accomplished by any suitable means including, but notlimited to, changing the temperature of the substrate support andflowing heated or cooled gases to the substrate surface. In someembodiments, the substrate support includes a heater/cooler which can becontrolled to change the substrate temperature conductively. In one ormore embodiments, the gases (either reactive gases or inert gases) beingemployed are heated or cooled to locally change the substratetemperature. In some embodiments, a heater/cooler is positioned withinthe chamber adjacent the substrate surface to convectively change thesubstrate temperature.

The substrate can also be stationary or rotated during processing. Arotating substrate can be rotated continuously or in discrete steps. Forexample, a substrate may be rotated throughout the entire process, orthe substrate can be rotated by a small amount between exposures todifferent reactive or purge gases. Rotating the substrate duringprocessing (either continuously or in steps) may help produce a moreuniform deposition or etch by minimizing the effect of, for example,local variability in gas flow geometries.

In atomic layer deposition type chambers, the substrate can be exposedto the first and second precursors either spatially or temporallyseparated processes. Temporal ALD is a traditional process in which thefirst precursor flows into the chamber to react with the surface. Thefirst precursor is purged from the chamber before flowing the secondprecursor. In spatial ALD, both the first and second precursors aresimultaneously flowed to the chamber but are separated spatially so thatthere is a region between the flows that prevents mixing of theprecursors. In spatial ALD, the substrate is moved relative to the gasdistribution plate, or vice-versa.

In embodiments, where one or more of the parts of the methods takesplace in one chamber, the process may be a spatial ALD process. Althoughone or more of the chemistries described above may not be compatible(i.e., result in reaction other than on the substrate surface and/ordeposit on the chamber), spatial separation ensures that the reagentsare not exposed to each in the gas phase. For example, temporal ALDinvolves the purging the deposition chamber. However, in practice it issometimes not possible to purge the excess reagent out of the chamberbefore flowing in additional regent. Therefore, any leftover reagent inthe chamber may react. With spatial separation, excess reagent does notneed to be purged, and cross-contamination is limited. Furthermore, alot of time can be used to purge a chamber, and therefore throughput canbe increased by eliminating the purge step.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A susceptor assembly comprising: a susceptorbase; a plurality of pie-shaped skins on the susceptor base, each of thepie-shaped skins having a recess; and a pie anchor in a center of thesusceptor base, the pie anchor configured to cooperatively interact withthe pie-shaped skins to hold the pie-shaped skins in place, wherein thepie anchor comprises at least one protrusion and the pie-shaped skin hasat least one recess adjacent an inner peripheral edge of the pie-shapedskin and sized to cooperatively interact with the at least oneprotrusion on the pie anchor, and the susceptor base comprises at leastone protrusion adjacent an outer peripheral edge and the pie-shaped skinhas at least one recess adjacent an outer peripheral edge of thepie-shaped skin and sized to cooperatively interact with the at leastone protrusion on the susceptor base.
 2. The susceptor assembly of claim1, wherein the recess has a depth substantially the same as a substrateto be positioned within the recess.
 3. The susceptor assembly of claim1, wherein the pie-shaped skin comprises a protrusion adjacent an innerperipheral edge and a protrusion adjacent an outer peripheral edge. 4.The susceptor assembly of claim 3, wherein the susceptor base has arecess adjacent an outer peripheral edge and the pie anchor comprises arecess positioned and sized to cooperatively interact with theprotrusions on the pie-shaped skin.
 5. The susceptor assembly of claim1, further comprising a clamp plate over the pie anchor and innerperipheral edge of the plurality of pie-shaped skins.
 6. The susceptorassembly of claim 1, wherein the susceptor base is made of a materialcomprising graphite.
 7. The susceptor assembly of claim 6, wherein thesusceptor base has a thickness in the range of 20 mm to 40 mm.
 8. Thesusceptor assembly of claim 1, wherein the pie-shaped skins are madefrom a material comprising a ceramic.
 9. The susceptor assembly of claim1, wherein the pie anchor comprises six protrusions and the pie-shapedskin has six recesses adjacent an inner peripheral edge of thepie-shaped skin and sized to cooperatively interact with each of the sixprotrusions on the pie anchor.